Preparation of-2-chloro-6-nitro-benzaldoxime



Patented Mar. 26, 1935 I TED No Drawing. I Application .Ju yfzr, 1933,;I i Serial No. 682,428

This invention relates to the preparation of 2 chlorofi-nitrobenzaldoxime which I have found to be a new and valuableintermediate for the preparation of certain dyestuffs. I

In my copending application Serial No. 682,427

filed of even date herewith, I have described the preparation of a newmercury compound of 2-. chloro-fi-nitrotoluene which is produced bythe.v action of nitrous acid on.2-chloro-6-nitrobenzaldimercurioxide,the preparation of which latter compound is described in my copendingapplication Serial No. 682,426. According to the preferred method forthe preparation of 2-chloro-.6- nitrobenzaldimercurioxide as outlined inthe example of application Ser. No. 682,426, 441 parts of pure freshlyprecipitated yellow mercuric oxide are stirred with 5000 parts of waterand 88 parts of flaked caustic soda andheated'toboil under a refluxcondenser. 171.5 parts of 2-ch1oro-6-nitrotoluene are added in smallamounts over a period of twelve hours While the temperature ismaintained at about 95 to 99 C. with continuous agitation; After theaddition is completed the mass is heated at 95 to 99 C. for twelve hoursor until all of the chloro-nitrotoluene has been reacted. The mass isthen cooled, filtered and the resulting solid dried at a lowtemperature. The product obtained when dry is an orange yellow powder,stable at ordinary temperatures. On heating it is decomposed. Theproduct is believed to be 2-chloro-6-nitrobenzaldimercurioxide of thefollowing probable formula According to the preferred method for theconversion of this compound to the corresponding nitrite, as found inthe specific example of U. S.

application Ser. No. 682,427,5865 parts of 2- product is a light yellowcrystalline powder which 1 starts to decompose at 50-60 C. and. has,very probably, the following formula:

According to the present invention, the nitrite compound of2-chloro-fi-nitrobenzaldimercurioxide as obtained aboveistreated,withhydrochloric acid, whereby it is split substantiallyquantita tively into 2-chloro-fi-nitrobenzaldoxime"' and 7 mercuricchloride. The mercuric chloride is obtained in such a form that it isreadily converted to mercuric oxide which may be used in thepre'paration of the starting material. 3

While Reissert. in Berichte volume 40, pages 4209-4226, hasdescribed thepreparation of Q2: vnitrobenzaldoxime from o-nitrotoluene by convertingit first to'the mercuric oxide-compound,

it was not to be expected that 2-chloro-6-nitrotoluene would react withmercuric oxide .to give a product that could be converted into2-chloro-6-nitrobenzaldoxime,for as disclosed by Reissert even p-nitrotolueneand2-4 dinitrotoluene would not react to give compounds from whichthea'ldoximes could be produced; V Y I In the decomposition: of thenitrite of the o-nitrobenzaldimercurioxide off Reissert a mixtureaccording to myprocedure very high yields of a substan-.

tially pure 2-chloro-fi-nitrobenzaldoxime are obtained. The aldoximewhich I have now produced.

is much more stable than the aldoxime produced by Reissert. I

lowing example is given in are by weight:

Erample To 225 parts of 16.3B.hydrochloric acid which is cooled to about10 C. are added alternately in To more fully illustrate my inventionthefolwhich the parts used small amounts, 481 parts of the nitritecompound of 2-chloro-fi-nitrobenzaldimercurioxide (above described) and750'parts of concentrated hydrochloric acid, 22 B., the temperaturebeing main{ tained at from 15-25 C. After the strong yellow color of thenitrite compound has disappeared the cream colored crystals arefiltered, washed with Water and dried. The product thus prepared has amelting point of 152-154 C. and upon recrystallization from toluene hasa melting point.

of 156- 15? C. V v

It is insoluble in cold water, soluble in hot water and in most of theorganic solvents. It is also soluble with a yellow color in dilutecaustic solution from which it can be precipitated with acid unchanged.The product has the following probable formula: V

Variousconcentrations of hydrochloric acid g may be used so vlong as theconcentr ation of the acid' in the reaction is maintained at about 25%;Ifthe dinitrite compound is used inthe wet form,

dry HCl may be added, Other acids such as sulj'furic; hydrobromic; etc.mai be used. The halo- 3 geriacids are. preferred over sulfuric acidsince fthey form mercury salts which are soluble inthe solution and areeasily separated from the al:

doxime; r The temperature during the decomposition should be maintainedatfrom 10,to 30 C. While I have described. aparticularprocess by I which2-chloro-6-nitrobenza1doxime may be prepared it 'will be obvious tothose skilled'in the art that various changes may be made without de-"1,996,007 a t n parting from the spirit of my invention and the V scopeof the following claims. a I claim: v

-3. Theprocessfor preparing 2-chloro-'6-nitrobenzaldoxime whichcomprises treating the nitrite compound of 2-chloro-6-nitrobenaaldimer-,

curioxide with hydrochloric acid of approximately 25% at atemperature-of 1525 C, f EMERICVHAVA' SL

